COLORADO SPRINGS, Colo.— The Center for Biological Diversity filed formal notices of intent to sue the Pike National Forest and Colorado Springs Utility today over rampant motorcycle use along Bear Creek, home to a highly unique population of federally threatened greenback cutthroat trout — a population some scientists believe to be a long-lost subspecies known as yellowfin cutthroat, not seen since the late 1800s.

“The population of cutthroat trout in Bear Creek is one of a kind and deserves better protection than it’s getting,” said Noah Greenwald, the Center’s endangered species director. “Heavy motorcycle use along the creek is hurting the trout and has to stop.”

There are only four populations of pure-strain greenback cutthroat trout in the world, and genetic studies suggest the Bear Creek population is unique — an irreplaceable element of Colorado’s natural history.

In recent years, the Forest Service has taken action to address the well-recognized impacts of motorcycles in Bear Creek, where steep slopes and fragile soils are a recipe for destruction by the vehicles, including building bridges to keep some crossings out of the stream. Despite these efforts, a habitat assessment conducted last year by an independent consultant found ongoing problems with motorcycles causing erosion into the creek, which smothers spawning beds and fills pools that provide critical habitat for the vanishing fish. Population surveys show the trout in steep decline in Bear Creek over the past few years.

“This problem can be solved by simply rerouting trails away from the creek and the trout,” said Greenwald. “We hope both the Forest Service and the utility will respond to the notices by taking urgently needed action to protect this disappearing fish.”

The notice to the Forest Service faults the agency for failing to consult with the U.S. Fish and Wildlife Service to ensure permitting of motorcycle use along Bear Creek does not jeopardize the trout, which is required under the Endangered Species Act. A separate notice faults the Colorado Springs Utility for harming the trout, in direct violation of the Act.